1. Field of the Invention
This invention is directed to a fence system and in particular to a novel fence post, a fence incorporating the post, being particularly suited for use as a snow fence, and to a method of erection thereof.
2. Background of the Invention
Widespread use is made in northern climates of snow fences. Snow fences are located to afford protection to selected areas, such as roads, etc., against drifting snow.
Snow fences operate by generating local turbulences in the prevailing wind, on passing through the elements of the fence, causing depostion of wind-born snow on the downwind side of the fence.
The best known and most widely used snow fence has been the vertically slatted fence, having wooden slats of about four feet in length carried upon twisted wire strands and supported between uniformly spaced fence posts. The slatted wooden fence normally is provided in fifty feet lengths, which forms an optimum sized roll constituting a suitable 2-man load.
Snow fences are erected to extend parallel with a road or other area being protected, and are generally located some 200 feet distant, upwind of the area to be protected against drifting. This generally causes them to be erected upon private property, and largely for this reason and by the fact of their location some way into fields and other areas bordering the road, it is usually imperative to install and remove the fences annually, on a seasonal basis.
Thus, the fence posts must be driven and the fences strung in late fall, and the process reversed, by removal thereof in the spring.
Owing to the significant bulk and not inconsiderably clumsiness of handling of the wood slat snow fences, their erection or removal requires the provision of truck transportation upon the land at climatically inopportune times, and the provision of three or four-man work crews is commonplace. One thousand feet of wood slat snow fence constitutes a normal truck load, of some twenty bulky rolls.
The performance of snow fences has received considerable theoretical study, both in Canada and the United States, including wind tunnel experiments of their characteristics and effectiveness. From the work of Threakston of Guelph University, Ontario, Canada and others, it appears to be fairly generally accepted that an ideal fence arrangement provides a 50/50 coverage, i.e., one half of the projected area of a section of fence is made up of a suitable form of slat, the other half of that area coverage comprising the space between adjacent slats.
It has been found that vertical slats tend to cause precipitation of snow unduly close to the fence line, with consequent loss of effectiveness, due to the formation of a deep drift immediately adjacent the fence line. In heavy snow fall areas, this can lead to a subsequent requirement to provide a second line of fence located upon the top of the first-formed drift, in order to maintain effective drift control. Timing of this requirement at the height of the snow season is most inopportune, and placement of the fence most awkward.
In contrast, snow fences of the type having horizontal slats have a more protective effect, thus generating snow deposition on a wider basis, with consequent delay in the build-up of a leeward bank, and thus extending the effectiveness of the snow fence.
The use of plastics for snow fencing is coming into its own. However, the matter of securing a net-like fencing to its supporting posts appears to have made little advance. The preferred known method appears to involve the use of a wood slat, sandwiching the net-like fencing between a wood strip and the fence post. This in turn generally requires that the fencing be tensioned for each span, as it is progressively nailed to the supporting posts, which constitutes a labour intensive operation.
The use of a horizontal plastic slat is known, in an embodiment utilizing a six inch width polyester tape as the slat. However, due to the material used, such slat provision is expensive, costing about one dollar Canadian per linear foot for a four slat polyester arrangement, exclusive of posts or post attachment systems. A like cost figure for the more usual vertical wood slat fencing would be in order of thirty-five cents to fifty cents Canadian per linear foot.
In addition, cost are further escalated, in the case of plastic "net" fences and polyester slat fencing, by the post attachment costs of the securing slats, and labour for this attachment.